What are "Tiers"?
As the title says, what are tiers? And also so you think it would be a good idea to start the English from Ukrainian course since I've gotten so far on the Ukrainian from English course?
Each language learner is assigned a tier representing the quality of their translations, as judged by other learners. Your progress within each tier depends on the votes your sentence translations receive from other learners in your tier or higher. You advance to the next tier once you have at least 100 upvotes and at least 90% of your votes are positive.
Because more accurate translations demonstrate greater proficiency in a language, learners at higher tiers earn more skill points for translating, editing, and rating others' translations.